1. Field of the invention
This invention relates, generally, to devices and methods having utility in the assembling of electric motors. More particularly, it relates to an apparatus and method for inserting coils on electric motor stators.
2. Description of the prior art
Electric motor stators are generally ring-shaped and include a plurality of equidistantly spaced apart, radially inwardly projecting teeth separated by slots. As is well known, coils of copper wire are inserted in the slots between the teeth. In the early days of electric motors, the coils were painstakingly inserted by hand, but machines for coiling the wire were eventually developed. However, the step of inserting the coils into the individual slots is still performed by hand in many applications.
One of the most helpful tools that has been developed is the coil insertion tool. It is a free standing device with a broad cylindrical base, a narrower cylindrical middle section, and a still narrower cylindrical top section.
Coils to be inserted into the slots between the stator teeth are first inserted onto the insertion tool. A typical coil assembly will include a plurality of looped sections in a circular pattern, i.e., the looped sections surround a central opening. This opening is slipped over the cylindrical middle section of the insertion tool, and the coil assembly is supported in that position by the broader base, i.e., the diameter of the central opening in the coil assembly is less than the diameter of the insertion tool base.
A cuff support tool having a central opening is then inserted over the top section of the insertion tool. A plurality of cuff support fingers extend radially inwardly from the central opening, and rest atop an annular shoulder formed where the top section of the insertion tool meets the middle section thereof.
Next, the stator is nested within the cuff support tool. In semi-automatic applications, a hydraulic ram is then used to pull the coils into their associated slots.
Where the above-described semi-automatic insertion is employed, a standard cuff support tool cannot be used. Instead, the cuff support teeth must be cammed radially inwardly and outward from the stator teeth. Such required special construction adds to the cost of making the cuff support tool, and as a result, semi-automatic coil insertion is seldom employed. Moreover, the known semi-automatic coil insertion tools require attachment to a machine, either for support or to facilitate operation. Nor do they protect the coils from abrasion at the time of insertion. They also do not provide proper containment of the lead end of the coils; this leads to the coils being hooked by the lacing needle.
There are numerous applications, however, where the cost of a machine that fully automates the coil insertion procedure cannot be justified. Thus, there is a need for an improved cuff support tool that is inexpensive to manufacture so that semi-automatic coil insertion could be economically performed. The ideal tool would be light-in-weight and would not require attachment to a machine for any reason. It would also protect the coils from abrasion when they are inserted into the stator. It would further provide lead end coil containment.
However, at the time the present invention was made, it was not obvious to those of ordinary skill in this are how an improved tool could be provided, in view of the art considered as a whole.